This invention relates to a switch, e.g. a power tool speed control switch having a housing and a terminal block and when arranged with a terminal clamping screw, which switch may possibly have to be transported from a supplier to the location of a customer where the screw is to be tightened in order to clamp a wire or other conductor terminal.
The switch and screw should preferably not be shipped separately, otherwise time is spent at the terminating location in finding and fitting the screw into the threaded hole.
Also the switch should not be shipped with the screw in its fully screwed in (and tightened down to the bottom) position, because it then has to be loosened and somewhat withdrawn at the terminating or customer location, in order to allow the conductor terminal to be inserted to its clamping position. Loosening, and partially withdrawing by the correct amount at the user location after shipping likewise takes substantial time and resources, e.g. for each power tool manufactured.
If, in an attempt to avoid such time losses, the switch is shipped with the screw initially partially screwed in, it will tend to loosen and fall out or even be lost.
It has been proposed in U.S. Pat. No. 3,585,332, believed to be the state of the art, to embed a plastics pellet, as a separate initial operation, in an external thread, to hold any position in the mating thread. This discloses also withdrawing a bolt one half turn from a fully home position. Although this reference deals with electrical terminals, it never considered shipping a clamping screw stably installed in a pre-clamping position.
It has also been disclosed, in U.S. Pat. No. 4,669,806, to use retaining projections in order to hold a clamping bolt against unwanted rotations, but not by engaging either thread. Also, because there is a clamp bracket which is installed before shipping and abutted, there is no requirement to ship a clamping screw in a stable ready-to-clamp position, which position would be identifiable only by the counted number of turns of relative displacement of the threaded members.